<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>核心选择器</title>
  <style>
    #two {
      color: aqua;
    }

    .one {
      color: azure !important;
    }

    p {
      background-color: bisque;
    }

    div.three {
      margin: 5px;

    }

    .one,
    #two {
      font-size: 25px;
    }

    * {
      margin: 0;
    }
  </style>
</head>

<body>
  <div class="one">one</div>
  <div id="two">two</div>
  <p>段落</p>
  <div class="three">1</div>
  <div class="three">2</div>
  <div class="three">3</div>
</body>

</html>